Resin laminated paper for photographic application



July 12, 1966 G. F. 1.. WOOD ETAL 3,

RESIN LAMINATED PAPER FOR PHOTOGRAPHIC APPLICATION Filed Jan. 4, 1962 '-R\ SILVER HAL/0E EMULSION '-V/ POLYETHYLENE 3 GLASS/IVE PAPER 4 \POLYETHYLE/VE 5 GLASS/IVE PAPER 6 POLYETHYLE/VE BACKCOAT GEORGE E L. W000 DOUGLAS G JOSEPH IN VEN TORS ATTOR/V Y5 United States Patent 3,260,602 RESIN LAMINATED PAPER FOR PHOTOGRAPHIC APPLICATION George F. L. Wood and Douglas C. Joseph, Rochester,

N.Y., assignors to Eastman Kodak Company, Rochester,

N .Y., a corporation of New Jersey Filed Jan. 4, 1962, Ser. No. 164,315 4 Claims. (Cl. 96-85) This invention concerns a photographic paper base which is water resistant, dimensionally stable and translucent, more particularly, a laminated-paper polyethylcue-composite photographic paper base.

It has been desirable to have photographic paper which is transparent for use with graphic arts processes and for use with diazo processes. The materials which are presently available are prepared with a translucent or transparent support such as glassine or transparentized paper which has been treated with various materials such as ralpha methyl styrene, cellulose esters and the like. However, many of these transparent bases are not sufficiently resistant to dimensional changes due to immersion in the processing solution, changes in relative humidity, and the like. Attempts to improve the dimensional stability of commercially available transparent paper have, in many cases, resulted in a decrease in the transparency. In other instances, the resulting product has been incompatible with photographic emulsions, has not been sufficiently stiff for satisfactory handling or has been too expensive to provide a commercial photographic element.

We have discovered a new photographic element which has the desirable degree of transparency, is dimensionally resistant to change and is stiff enough to be suitable for graphic arts processes.

One object of this invention is to provide a transparent or translucent photographic base which is water resistant and dimensionally stable. Another object is to provide a paper base which has sufficient stiffness, dimensional stability and translucency necessary for a photographic intermediate used for making additional copies such as used in the diazo systems. A further object is to provide a laminated photographic paper which is photographically inert, which is water resistant, and which is inexpensive to manufacture.

The above objects are obtained by adhering two sheets of glassine paper together by means of a polyethylene film followed by coating polyethylene on the exterior surfaces of the glassine sheets.

The glassine paper is obtained by well-known methods and may have a weight of 35 lbs./ 1000 sq. ft. The thickness of the polyethylene film between the two sheets of glassine paper may be from .4-1.5 mil in thickness, and the thickness on the exterior surfaces of the polyethylene coatings may be from 0.4-1.0 mil in thickness. The polyethylene coatings may be applied by conventional methods, but in our preferred embodiment we extrude the molten polyethylene between the two sheets of glassine paper and coat the polyethylene on the exterior surfaces by extrusion coating applications. It will be clear that other methods such as solvent, dispersion, or the like may be used for coating the polyethylene. The composite of two glassine sheets having the polyethylene adhering them together may also be obtained by coating one sheet and contacting it against the other using heat and/ or pressure.

Various types of polyethylene may be employed, but our preferred embodiment is low density, extrusion coating grade. Medium and high density polyethylene have also been used successfully.

3,260,602 Patented July 12, 1966 In order to prepare the photographic product, it is necessary to treat the polyethylene surface to render it sufficiently hydrophilic to obtain adhesion. We prefer to use the electron-bombardment method to obtain adhesion to gelatino coating compositions. Other surface treatments may be used to obtain adhesion such as the flame treatment of the polymeric surface, oxidation using a sulfuric acid-dichromate solution, contacting with chlorine gas, treating with peroxide, and the like.

A sectional view of one embodiment of our invention is illustrated by the drawing. A light-sensitive silver halide emulsion 1, is coated on the top layer of a series of substrates in combination comprising first a polyethylene substrate 2, glassine paper 3, polyethylene 4, glassine paper 5, polyethylene 6, and having a backcoat 7.

Another embodiment of our invention may be obtained by omitting the backcoat.

The following examples are intended to illustrate our invention but not to limit it in any way:

Example 1 A 4 lbs/1000 sq. ft. glassine paper was laminated to another sheet of similar glassine paper with a 1 mil lowdensity polyethylene film on a conventional extrusion coating machine by extruding the polyethylene into the nip as the 2 sheets were passed between a pair of rollers. This laminate was then coated on both sides with polyethylene. One of the polyethylene coated surfaces was treated with high energy electron bombardment for emulsion adhesion. A high contrast projection speed light sensitive silver halide was then coated over the treated surface.

The sensitized product has a high degree of wet stiifness, dimensional stability, and drying rate as compared to customary photographic paper base, under normal processing and operating conditions.

Example 2 A product was prepared as in Example 1 except that a high density polyethylene was used instead of low density polyethylene for the lamination and surface coatings. The product had improved stiffness and water resistance.

Example 3 A 5 lbs/1000 sq. ft. glassine sheet is laminated to a similar sheet with a low viscosity, high melt index polyethylene by applying a hot melt coating to one sheet of the glassine paper and contacting the coating paper against the second sheet of glassine paper. While the coating is in a heated condition, pressure is applied by means of heated rollers through which the laminate is passed. The laminate is then extrusion coated with 2 lbs./ 1000 sq. ft. of high density polyethylene on each side. After an electron bombardment treatment, the treated surface is coated with a light-sensitive silver halide emulsion and has satisfactory stiffness, water resistance, and dimensional stability.

Example 4 A product was prepared the same as in Example 1 except that a washoff type of photographic emulsion was used for sensitizing the paper base and to obtain a direct positive image.

Example 5 Products were prepared as in Examples 1 and 3 except that both sides of the laminate were treated using electron bombardment and an antihalation, antistatic, anticurl coating was applied on the side opposite the emul- Mn was dispersed in the gelatin to produce a dark 'brown color that gives .5 to .7 density to blue light. The MnO is dispersed in such a form as to react with the sodium thiosulfate of the fixing solution to produce a colorless complex. The gelatin was applied and hardened in the same manner as the gelatin of the silver emulsion on the opposite side in an attempt to produce a force equal and opposite to the gelatin of the emulsion.

Other backcoats may be used in place of the above. In the event that antihal ation protection is not necessary, the MnO may be omitted.

In our preferred embodiment, we use a high contrast, projection speed chlorobrornide light-sensitive silver emulsion; however, other light-sensitive silver halide emulsions may be used depending upon the purpose for which the product is to be used. For instance, both black and White emulsions may be used including silver iodide emulsions, silver chloride emulsions, silver bromide emulsions, and emulsions which contain mixtures of these light sensitive silver salts.

Photographic paper prepared according to our invention is free from curl, has a high degree of translucency and is free from such defects as staining, edge penetration, and the like.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it Will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A photographic paper base comprising in combination two sheets of glassine paper adhered to each other by a film of polyethylene and having a polyethylene film coated on the exterior surfaces of the glassine paper.

2. A photographic paper base comprising two sheets of 35 lbs./ 1000 sq. ft. gl'asisne paper adhered to each other by a layer of .4-1.5 mil thick polyethylene and having 0.3-1 mil thick polyethylene coated on the exterior surfaces of the glassine paper.

3. A photographic paper as described in claim 2 having coated thereon :a light-sensitive silver halide emulsion.

4. A photographic paper as described in claim 3 having a backcoat coated on the side opposite the silver halide emulsion.

References Cited by the Examiner UNITED STATES PATENTS 2,875,055 2/1959 Griggs et al. 9685 2,930,727 3/1960 Baranyi l5446 2,991,208 7/1961 Stieger 15446 3,021,214 2/1962 Murphy et a1 9685 3,037,862 6/1962 Neth 9675 3,169,865 2/1965 Wood 9685 NORMAN G. TORCH'IN, Primary Examiner.

J. T. BROWN, R. H. SMITH, Assistant Examiners. 

1. A PHOTOGRAPHIC PAPER BASE COMPRISING IN COMBINATION TWO SHEETS OF GLASSINE PAPER ADHERED TO EACH OTHER BY A FILM OF POLYETHYLENE AND HAVING A POLYETHYLENE FILM COATED ON THE EXTERIOR SURFACES OF THE GLASSINE PAPER. 